Just wondering about how long it takes for vented rotors to rust so they can not be used. I know depends on salt in air, moisture etc. But a lot of those imports you see with rusted rotors, do you usually just give the pad contacting area a gouge with something to check thickness of rust?
surface rust usually goes after 5mins of driving. Anything worse they can be machined. Only ever really become useless when they are undersize or cracked.